SK720BE Mounting (Pads)

[Scallybert]

Since my first SK720 ‘blue’s, I’ve always mounted using thethick (~4mm) spongey pads supplied, and it’s worked well.

These pads now seem hard to come by.

The FAQ suggests hard mounting SK540s, but using the fullant-vibration kit for SK720s.

Is the latter appropriate advice for mounting SK720 Blacks ?Or can they also be hard mounted on electric helis ?

[What’s prompted this is the need to remount an SK720BE,that was fine on a 4mm pad. I have no more of these pads, so used a roughlysimilar pad. Unfortunately, this *seems* to have doubled the vibrationreading from ~7.5 to 15. Interestingly, the ‘similar’ pad appeared softer – sothe vibe increase is partially counter-intuitive. So, I’m wondering what thecurrent recommendation is.]

[Luvmyhelis]

Originally Posted by Scallybert

Since my first SK720 ‘blue’s, I’ve always mounted using thethick (~4mm) spongey pads supplied, and it’s worked well.

These pads now seem hard to come by.

The FAQ suggests hard mounting SK540s, but using the fullant-vibration kit for SK720s.

Is the latter appropriate advice for mounting SK720 Blacks ?Or can they also be hard mounted on electric helis ?

[What’s prompted this is the need to remount an SK720BE,that was fine on a 4mm pad. I have no more of these pads, so used a roughlysimilar pad. Unfortunately, this *seems* to have doubled the vibrationreading from ~7.5 to 15. Interestingly, the ‘similar’ pad appeared softer – sothe vibe increase is partially counter-intuitive. So, I’m wondering what thecurrent recommendation is.]

You can hard mount the 720B, but be aware the self level bail out may not be reliable. Or really won't be with those vibe readings you posted. But otherwise they will fly well as any other gyro out there. Quite a few different style foam pads work well. We have played with dozens of different variations here in these threads over the years. I myself spent years trying different mounting methods and pads. Gels, hard, soft foams, combos. I tend to vary the method depending on the heli the 720 is mounted on. But overall the best average seems to be to use the harder foams and address the vibes to allow you to use them. I found some decent 4mm stuff that is pretty dense at a local hardware store. Make sure the adhesive on the padding is good! The last couple batches of Skookum strips were notorious for letting go, I could set my helis upside down in the heat and the 720s would fall off all by themselves if left there for long.

[Scallybert]

Originally Posted by Luvmyhelis

[...]The last couple batches of Skookum strips were notorious for letting go, I could set my helis upside down in the heat and the 720s would fall off all by themselves if left there for long.

Yep, that's exactly what happened, to prompt replacing this Skookum pad.

Fast inverted '8's, and suddenly we have horrendous tail shake. Didn't go away when I went into a 'low gain safety mode'. But calmed down when I rolled into non-inverted. I suspect itself stuck back on the pad..!

I suppose what I'd like, is a pad like the Skookum ones - but sticky.

[dcope17]

With a softer mounting pad you changed the resonant frequency of the Skookum 720. A common misconception is that softer is better but if you are getting the resonant frequency closer to the frequency of the heli vibes, it will show an increase in the vibe log.
Do some testing with different mounting pads and use what works best. It is purely a trial and error type of thing and you cannot predict the results with any accuracy. Just test it, try something different then compare.

[A VIKING]

Originally Posted by dcope17

With a softer mounting pad you changed the resonant frequency of the Skookum 720. A common misconception is that softer is better but if you are getting the resonant frequency closer to the frequency of the heli vibes, it will show an increase in the vibe log.
Do some testing with different mounting pads and use what works best. It is purely a trial and error type of thing and you cannot predict the results with any accuracy. Just test it, try something different then compare.

100% agreed.
Its a little science with a lot of Voodoo.

[Scallybert]

I appreciate the pad is effectively a spring-damper combination, to decouple the SK from the heli; and that decoupling behaviour will be frequency dependant.

FWIW, and from memory, the major vibes were about 200 Hz [close to 12000 RPM, tail rotor]; and vertical.

I think the most useful information would be if people have specific (available..!) pads they're using to mount their SK720BEs. [I do appreciate that different vibe regimes will make a difference.]

[Luvmyhelis]

Originally Posted by dcope17

With a softer mounting pad you changed the resonant frequency of the Skookum 720. A common misconception is that softer is better but if you are getting the resonant frequency closer to the frequency of the heli vibes, it will show an increase in the vibe log.
Do some testing with different mounting pads and use what works best. It is purely a trial and error type of thing and you cannot predict the results with any accuracy. Just test it, try something different then compare.

Pretty much the only thing bad we noticed about a softer pad is the helis tend to overshoot slightly during hard moves. Not so great for piros and tic tocs. Also, each density of foam will dampen out specific frequencies. No two act the same.
Wanted to note here, that if you do have a pad material that has so so adhesive, just find thin adhesive tape with great properties and add that to both sides. I bought a big roll of tape on a one day sale years ago that is bullet proof, great for hard mounting just about everything, and also great for addressing poor adhesive vibe padding. After my own Skookum tape let go on my Gob 700, totalling the heli, I used this tape on the last of my Skookum tape after that and never had any issues.

Back in the 'good old days' when we flew flying crap basically. And for nitro guys. We used to stack pads with thin metal plates in between hard/soft gel and/or foam layers. I kept pages of logs using dozens of different pads and techniques I and other guys here tried on just about every heli out there. We could dampen out certain frequencies almost entirely. Today's helis are light years better. I deleted those logs years ago.

[Machinehead01]

Of changing the pads, I have found that putting Scotch, or the 2 inch wide packing tape on the underside of the controller and on the top of the heli's gyro pad to the faster, less painful way of the on and off again controller pad shuffle. The tape is much easier to remove from the hard surfaces then the pads are but yet still enable the pads to have a good solid bite to both surfaces.

Just my 2 cents worth. Tom

[Necroscope]

I glued 3m double sided tape on to each side of a peice of dense foam from an Align servo box. This was on a 450L. Worked bloody well, and had a vibe score of 0.75 to 1.5.